Curing oven for enameled wire

ABSTRACT

An elongated casing includes partitions dividing the interior of the casing into an elongated work chamber, combustor inlet and outlet chambers, and gas passageways. The work chamber has opposite open inlet and outlet ends for passage of coated wire through the work chamber, and an elongated combustor tube has opposite gas inlet and outlet ends in the combustor inlet and outlet chamber respectively. A blower in the combustor outlet chamber receives air and other gases from the combustor outlet chamber and moves the same through some of the passageways to the inlet and outlet ends of the work chamber, some of the partitions directing flow of the gases inwardly from the inlet and outlet ends of the work chamber to an inlet passageway leading from the intermediate portion of the work chamber to the combustor inlet chamber. The casing defines air inlet opening to the combustor outlet chamber and a discharge opening to the exterior of the casing from one of the passageways between the blower and the work chamber. The burner is mounted at the inlet end of the combustor tube and receives combustion supporting air only from the work chamber, such air being laden with fumes evaporating from the enamel or similar coating on wire moving through the work chamber.

United States Patent [191 Dumas [451 May 14,1974

' CURING OVEN FOR ENAMELED WIRE [75] Inventor: Floyd A. Dumas, Hamel, Minn.

[73] Assignee: Acrometal Products, Inc.,

Minneapolis, Minn.

[22] Filed: Aug. 31, 1973 [21] Appl. No.: 393,616

Primary Examiner-John .l. Cam by Attorney, Agent, or Firm-Merchant, Gould, Smith &

Edell 571 [ABSTRACT An elongated casingincludes partitions dividing the interior of the casing into an elongated work chamber, combustor inlet and outlet chambers, and gas passageways. The work chambervhas opposite open inlet and outlet ends for passage of coated wire through the work chamber, and an elongated combustor tube has opposite gas inlet and outlet ends in the combustor inlet and outlet chamber respectively. A blower in the combustor outlet chamber receives air and other gases from the combustor outlet chamber and moves the same through some of the passageways to the inlet and outlet ends of the work chamber, some of the partitions directing flow of the gases inwardly from the inlet and outlet ends of the work chamber to an inlet passageway leading from the intermediate portion of the work chamber to the combustor inlet chamber. The casing defines air inlet opening to the combustor outlet chamber and a discharge opening to the exterior of the casing'from one of the passageways between the blower and the work chamber. The burner is mounted at the inlet end of the combustor tube and receives combustion supporting air only from the work chamber, such air being laden with fumes evaporating from the enamel or similar coating on wire moving through the work chamber.

11 Claims, 5 Drawing Figures MTENTEDIIAY 14 (I974 SHEET 3 OF 3 l CURING OVEN FOR ENAMELED WIRE BACKGROUND OF THE INVENTION This invention is in the nature ofan improvement over curing ovens generally of the type disclosed in U.S. letters Pat. 3,106,386, issued to Edward H. Harris,

- assignor to the assignee company of this invention. In

the curing oven of U.S. Pat. No. 3,106,383, and some others, heated air from the work chamber is subject to the flame of a burner which partially oxidizes the fumes released from the enamel or other coating material and carried by the air to a combustion chamber. The heated air, still laden with some unoxidized fumes, is then passed through a catalyst which oxidizes the remaining fumes. The use of a suitable catalyst generally involves a substantial initial expense in the construction of the curing oven, and also necessitates periodic shutdown of the apparatus for servicing of the catalyst to remove deposits accumulating thereon.

An important object of this invention is the provision of a curing oven for enameled wire in which the volatile fumes released bythe drying, coating material is subject to the flame of aburner for a length of time sufficient to substantially completely oxidize or consume the fumes, to the extent that they are neither harmful nor objectionable.

Another object of this invention is the provision of a curing oven which eliminates the necessity, for a catalyst to achieve complete oxidation of the fumes.

Another object of this invention is the provision of a novel burner construction for oxidizing fumes and for heating the gases used in the drying and curing process.

Another object of this invention is the provision of wall structure or dividing the wire receiving work chamber into a pair of spaced operating zones for efficient drying and curing of the'wire coating material.

To the above ends, I provide a curing oven for wire coating material, the oven including a casing having partitions dividing the interior of the casing into a wire receiving work chamber, a combustor section having combustor inlet and outlet chambers and the passageways between the work chamber and the combustor inlet and outlet chambers. An elongatedcombustor tube has opposite inlet and outlet ends in the inlet and outlet chambers respectively, and a burner in its inlet end. The work chamber has opposite open inlet and outletends and is formed to provide an intermediate restricted portion which divides the work chamber into an evaporating zone inwardly of the inlet end and a curing zone inwardly of the outlet end. An inlet passageway leads from the intermediate portion to the combustor inlet chamber. A blower in the combustor outlet chamber forces heated gases under pressure through outlet passageways leading to the'work chamber adjacent the inlet and outlet ends, the gasesbeing directed tor inlet chamber. The casing has a pair of fresh air inlet openings to the combustor outlet chamber and a discharge opening from one of the outlet passages to the exterior of the oven for controlled addition of fresh air to the gases-flowing through the oven.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section of a curing oven produced in accordance with this invention, taken on the line l-1 of FIG. 2, some parts being broken away.

FIG. 2 isa horizontal section, taken substantially on the line 2-2 of FIG. 1, some parts beingv broken away;

FIG. 3 is an enlarged fragmentary section taken substantially on the line 3--3 of FIG. 1;

FIG. 4 is an enlarged fragmentary section taken on the line 44 of FIG. 1; and 7 FIG. 5 is a fragmentary section taken substantially on the line 55 of FIG. 1.

DETAILED DESCRIPTION OF TI-IE PREFERRED EMBODIMENT The curing oven of this invention is generally rectangular in form, the same comprising a casing 1 having spaced front and rear walls 2 and 3 respectively, laterally spaced vertical side walls 4 and 5, and top and bottom walls 6 and 7 respectively. The front wall 2 comprises a plurality of vertically spaced generally horizontal cross members 8, suitably connected at their opposite ends tothe side walls 4 and 5, and a plurality of plate-like closure members 9 and 10. The rear wall 3 includes a pair of upper and lower wall sections 11 and 12 respectively, the upper wall section 11 being forwardly displaced with respect to the lower rear wall section 12. The upper edge of the wall section 12 is connected to the lower edge of the wall section II by a horizontally disposed wall member 13. Preferably, and as shown, the above-described walls and closure plates are of double wall construction, each thereof having inner and outer layers of sheet metal, the space therebetween being filled with suitable insulating material.

The interior of the casing I is divided into several chambers and passageways by a plurality of partitions. A pair of vertically disposed insulated partition members I4 and I5 cooperate with portions of the side walls 4 and 5, bottom wall 7, rear wall section 12 and wall member 13 to define a vertically extended combustor chamber 16 that is divided by a horizontally disposed partition member 17 into an upper combustor inlet chamber 18 and a lower combustor outlet chamber I9.

A hollow partition 20 is disposed between the upper rear wall section 11 and the uppermost closure plate 9, the partition 20 having the front wall 21 in rearwardly spaced parallel relation to the front casing wall 2, and a rear wall 22 in forwardly spaced relation to the rear casing wall section 11. The lower end of the hollow partition 20 rests on art insulated cross member 23 that extends generally horizontally between the side walls 4 and 5 in forwardly spaced relation to the forward edge of thehorizontal wall member 13. The cross member toward the inlet passageway for return to the combus- 23 forms the upper end of a second hollow partition 24 having front and rear walls 25 and 26 respectively that are vertically aligned with respective ones of the walls 21 and 22. The lower edges of the partition walls 14, 25 and 26 are connected by a generally horizontal wall 27 disposed in overlying spaced parallel relation to the partition member 17. A vertical insulated partition 28 extends upwardly from the bottom casing wall 7 to the partition member I7, the partition 28 having a front wall 29 that is aligned with the partition walls 21 and 25. The walls 21, 25 and 29 cooperate with the front casing wall 2 and the front portions of the side walls 4 and to define a work chamber 30 that has an open inlet end 31 adjacent the bottom wall 7, and an open outlet end 32 adjacent the top casing wall 6. The work chamber 30 is generally rectangular in cross section and is adapted to receive a plurality of enameled or otherwise coated wires 33 running longitudinally therethrough in laterally spaced parallel relationship, as shown in FIGS. 1 and 2. A vertical partition 34 is disposed between the bottom casing wall 7 and partition member 17 and extends transversely of the casing 1 from the side wall 4 to the side wall 5 thereof. The partition 34 is preferably disposed in vertical alignment with the partition walls 22 and 24, and, adjacent its lower edge, is provided with a plurality of perforations 35. It will be here noted, that the partition wall 26 is also perforated, as indicated at 36.

The upper end portion of the partition 28 is provided with a forwardly projecting portion 37 that cooperates with a rearwardly projecting wall portion 38 of the closure plate and a cross-sectionally generally triangular cross member 39 to form a restriction 40 in the work chamber 30 intermediate the open ends 31 and 32 thereof. The restricted portion 40 divides the work chamber 30 into a lower evaporating zone 41 extending inwardly from the inlet 31, and a curing zone 42 that extends longitudinally inwardly from the outlet end 32. The cross member 39 cooperates with the forward end portion of the partition member 17 and the horizontal wall 27 to define rearwardly converging portions of an inlet passageway 43 leading from the work chamber 30 to the combustor inlet chamber 18. A conventional blower or fan 44 is disposed in the combustor outlet chamber 19 adjacent the side wall 5 and bottom wall 7 ofthe casing l, and is adapted to be driven by a motor 45 mounted on the side wall 5, see FIG. 2. The blower 44 forms a portion of an outlet passage 46 that extends from the combustor outlet chamber 19 between the partition members and 34, through a plurality of laterally spaced tubular connectors 47 extending between the partition member 17 and wall 27, between .the partition member 14 and partition wall 26 and between the partition 20, rear wall section 11 and top wall 6 to the upper end portion of the work chamber curing zone 42 inwardly of the outlet end 32 thereof. A branch passageway 48 within the partition 24 communicates with the passageway 46 by means of the perforations 36 in the partition wall 26, and with a discharge opening 49 extending through the side wall 4 to the exterior of the casing 1. A second branch passage 50 is defined by the partitions 28 and 34 and communicates with the passagewa'y 46 through the perforations 35 in the partition 34. The branch passageway 50 communicates with the work chamber evaporating zone 41 by means of pairs of upper and lower openings 51 and 52 respectively through the partition 28. Pairs of upper and lower dampers 54 and 55 respectively are operable to control passage of air from the branch passageway 50 to the work chamber evaporating zone 41. The dampers 54 and 55 are operated by suitable means, such as control knobs or the like 56 at the exterior of the casing 1. The branch passageway 50 also communicates with the inlet passageway 43 through an elongated slot-like opening 57 in the partition member 17. Perforated horizontal and vertical plates 58 and 59 respectively are disposed in the lower portion of the passageway 46 to aid in distributing air pressures equally over the areas of the passageways 46 and 50, and a damper 60 is dis posed near the upper end of the passageway 46 to aid in controlling the delivery of air to the upper end portion of the work chamber curing zone 42. It will be noted that the openings 51 and 52 in the partition 28 slope forwardly and upwardly to direct the air flowing therethrough in an upward direction toward the restricted portion 40. A baffle member 61 secured to the top wall 6 aids in directing air from the upper end of the passageway 46 downwardly into the work chamber 30.

An elongated combustor tube 62 extends longitudinally of the combustor chamber 16 having an upper inlet end projecting through an opening 63 in the hori' zontal wall member 13 and provided with a mounting flange 64 that is secured to the horizontal wall member 13 by machine screws or the like 65 to suspend the combustor tube 62 in the combustor chamber 16. The tube 62 extends downwardly through a suitable opening in the partition member 17, and has its lower open end 66 disposed in upwardly spaced relation to the bottom wall 7. With reference to FIG. 2, it will be seen that the combustor tube 62 is disposed in relatively-closely spaced relation to the sidewall 4 and in relatively widely spaced relationship to the blower 44, whereby to provide a substantial area for flow of air and other gases between the combustor tube 62 and the blower 44. As shown in FIG. 1, the partition member 17 is reinforced by a circular angle member 67, the combustor tube being provided with a pair of axially spaced flange members 68 and 69 the former of which rests upon a gasket or the like 70 overlying the angle member 67, and the latter being disposed in underlying engagement with the bottom surface of the partition member 17 to seal the opening through which the combustor tube 62 extends, the opening being shown fragmentarily in FIG. 1 and indicated at 71. Adjacent its upper end, the combustor tube 62 is provided with a plurality of circumferentially spaced inlet openings 72 extending radially therethrough.

A burner, indicated generally at 73, is disposed in the upper inlet end of the combustor tube 62, and comprises a header 74 having inner and outer cylindrical walls 75 and 76 respectively, and axially spaced outer end walls 77 and 78 extending transversely of the cylindrical walls 75 and 76 respectively. A fluid fuel inlet tube 79 extends axially outwardly of the transverse wall 78. A transverse inner wall 80 is secured to the inner end of the inner cylindrical wall 75, and to the inner surface of the outer cylindrical wall 76, the wall 76 extending axially inwardly of the transverse wall 80 to provide a cylindrical skirt 81 having an open axially inner end 82. The skirt 81 is provided with aplurality of axially spaced rows of circumferentially spaced openings 83. A plurality of circumferentially spaced burner tubes 84 extend longitudinally of the skirt 81 and are secured thereto, preferably by welding or the like, each of the burner tubes 84 having axially spaced slots 85 directed radially inwardly toward the axis of the skirt 81. Each burner tube 84 has an inner end secured to the axially inner wall 80 of the header 73, the inner end of each burner tube 84 communicating with annular fuel passage 86 defined by the cylindrical walls 75 and 76 of the header 74. The annular passage 86 communicates with the inlet tube 79 by means of a transverse passage portion 87 between the axially spaced walls 77 and 78 of the header 74. The inner ends of the burner tubes 84 are closed by plugs or wall portions 88. Preferably, the space inwardly of the inner cylindrical wall ,75, between the transverse walls 77 and 80, is filled with suitable heat insulating material 89 Means for mounting the burner 73 axially in the inlet end portion of the combustor tube 62 comprises a generally cylindrical burner mounting conduit 90 that encompasses the burner 73. The mounting conduit 90 includes an outer cylindrical wall 91 having axially spaced rows of circumferentially spaced openings 92 therein, a transverse outer end wall 93 having an axial burner receiving opening 94 therein, and an axially inner end wall 95 including axially spaced radially outer and inner annular wall sections 96 and-97 connected by a cylindrical wall section 98, see particularly FIG. 4. The radially inner annular wall section 97 defines an axial opening 99. The outer end wall 93 is mountedon the combustor tube flange 64 by means of a plurality of circumferentially spaced mounting screws 100, the annular inner end wall section 96 operatively I axial opening 94. Circumferentially spaced brace members 106 are secured to the endwall 93 and partition 105 to hold the same in axially spaced apart relationship, the space between the end wall 93 and partition 105 being at least partially filled with insulating material, indicated at. 107.

As shown particularly in FIG. 4, theburner 73 is axially disposed in the opening 94 and is mounted therein for movements axially of the mounting conduit 90 and combustor tube 62. An annular guide flange 108 is bolted or otherwise rigidly secured to the outer. end wall 93, and encompasses the header 74 to hold the same in coaxial relationship with the conduit 90. Means for axially adjusting the burner 73 comprises a pair of adjustment screws 109 each carried by a different one ofa pair of supporting arms 110 that are secured to the outer end wall 93 by anchoring screws 111 and spacer blocks 112. The adjustment screws extend longitudinally of the burner 73 and have screw threaded engagement with nut elements 113 rigidly secured to the header wall 78. A pair of stop screws 114 are each screw threaded in a different one of the arms 110 in spaced parallel relationship to a different one of the adjustment screws 109, the inner ends of the stop screws 114 engaging the outer surface of the transverse wall 78, the stop screws 114 cooperating with theadjustment screws 109 to releasably lock the burner 73 in adjusted positions axially of the mounting conduit 90.

The burner mounting conduit 90 further includes a plurality of circumferentially spaced vanes 115 that extend longitudinally between the annular wall section 96 and partition 105, and which are disposed in a generally spiral arrangement, projecting inwardly from the outer cylindrical wall 91 to the extended cylindrical plane of the cylindrical wall section 98, see particularly FIG. 3. A second plurality of generally flat vanes 116 project radially inwardly from the cylindrical wall section 98, and have radially inner edges disposed in closely radially outwardly spaced relationship to the burner skirt 81, adjacent its open inner end 82. With reference to FIG. 4, it will be seen that the vanes 116 extend longitudinally of the burner mounting conduit 90 from the inner end wall section 97 to the annular wall section 96.

A pair of air inlet tubes 117 and 118 extend through the rear casing wall 3 from the exterior of the casing l to the combustor outlet chamber 19, the inlet tube 117 being disposed close to the casing side wall 4 and the partition member 17, the inlet tube 118 being disposed in closely spaced relationship to the blower 44 and having its inner end closeto the inlet portion of the blower 44. The inlet tubes 117 and 118 are provided with damper plates 119 and 120 respectively, that are connected by means of links 121 toa crank member 122 that is driven by suitable operating means not shown,- but contained within a housing 123 mounted on the rear wall 3. The mechanism within the housing 123 does not in and of itself comprise the instant invention, hence, further detailed showing and description thereof is omitted in the interest of brevity. It should suffice to state that the mechanism is operative to move the damper plates 119 and 120 in directions to control entry of fresh air to the chamber 19 through their respective inlet tubes 117 and 118.

OPERATION Assuming that lengths of wire 33 are being fed through the work chamber 30 in an upward direction with respect to FIG. 1, and that the burner 73 is ignited and the blower motor 45 is energized, air and gases are drawn into the blower 44 through the inlet tubes 117 and 118 and combustor tube 62 respectively, and are forced outwardly of the blower 44 through the passages 46 and 50 to the evaporating zone 41 and curing zone 42, the heated air causing rapid evaporation of the volatile portions of the coating on the wires 33. The vapor laden air flows through the inlet passageway 43 to the combustor inlet chamber 18, the temperature of the vapor laden air rising due to heat radiating from the upper portion of the combustor tube 62. The vapor laden air flows radially inwardly through the inlet openings 72 in the combustor tube 62 and radially inwardly through the openings 92 in the mounting conduit wall 91, where it impinges on the vanes 115 and partakes of generally spiral inward movement toward the burner skirt 81. Some of the vapor laden air flows-radially inwardly through the openings 83 in the skirt 81 to the interior of the burner, operating asprimary combustion supporting air for the fluid fuel flowing generally radially inwardly through the slots in the burner tubes 84. The flame within the' burner 73 heats the air within the skirt 81 to the combustion temperature of the vapor carried by the air, so that the vapor acts as additional fuel for the burner. The vapor laden air within the mounting conduit which does not enter the burner 73 flows downwardly past the vanes 116. to the axial opening 99 in the inner wall section 97, where it joins the burning gases flowing downwardly through the open inner end 82 of the skirt 81, the vapor carried by the air being heated to, its combustion temperature as it passes downwardly through the outlet opening 99 and becoming thoroughly oxidized as it passes downwardly through the combustor tube 62.

As the vapor laden air passes inwardly through the openings 92 in the mounting conduit 90, the flow thereof becomes subject to extreme turbulence due to impingement of the air on the vanes 115. This extreme turbulence causes the air flowing downwardly past the vanes 116 to become thoroughly mixed with the burning gases flowing downwardly through the open end 82 of the burner 73, so that thorough combustion and oxidation of the vapors or fumes is assured.

it will be noted that movement of gases inwardly through the evaporating and curing chambers toward the inlet passageway 43, causes some air to be drawn inwardly through the inlet and outlet ends 31 and 32 respectively of the work chamber 30. The dampers 54, 55 and 60 in the passageways 50 and 46 respectively are used to vary the flow of air and gases of combustion to the evaporating and curing zones of the work chamber 30. When the dampers 54 and 55 are moved toward their closed positions, relative to the openings 51 and 52, some of the gases flowing through the passageway 50 will bypass the evaporating chamber 41 and return to the inlet passageway 43 through the slot 57 in the partition member 17. Other air and gas mixture flowing upwardly through the passageway 46 and tubular connectors 47 is bypassed through the openings 36 in the wall 26, through the branch passageway 48 and outwardly of the casing 1 through the discharge opening 49.

It will be appreciated that, not only do'the air inlet tubes 117 and 118 cooperate with the open ends of the work chamber 30 to provide fresh air for the system, but they also operate to control the temperature of the air and gas mixture flowing from the combustor outlet chamber 19 to the work chamber 30. It will be appreciated that the temperatures required to satsifactorily cure the coating material is considerably lower than the temperature required to oxidize the hydrocarbons which comprise the-solvents evaporated from the coatings. Thus, as the gases of combustion enter the outlet chamber 19, from the combustor tube 62, they are cooled by fresh air entering the combustor outlet chamber 19 through one or both of the inlet tubes 7 and 118. Then, when the vapor laden air and gas enters the inlet chamber 16 and the inlet openings 72 of the combustor tube 62, these gases become heated by the burner 73 to the combustion temperature ofthc solvent so that thorough oxidation ofthe solvents occurs within the combustor tube 62. lt will be further noted that, inasmuch as pressure is drawn into the system through the inlet tubes 117 and 118, as well as through the open opposite ends of the work chamber 30, the excess air and thoroughly oxidized gas is forced outwardly through the perforations 36 in the partition wall 26 and outwardly ofthe easing 1 through the passageway 48 and discharge opening 49. Axial adjustment of the burner 73 with respect to its burner mounting tube 90 varies the amount of air and gas entering the interior of the skirt 8] through the openings 83 therein, relative to the amount of air moving downwardly past the vanes 116, so that an optimum mixture of vapor laden air and gas and fluid fuel within the burner skirt 81 may be obtained. Further, axial adjustment of the burner 73 relative to the mounting tube 90 causes a variation in the gap between the discharge end of the skirt 81 and the inner end wall section 97, to vary the rate of flow of gases through the combustor tube 62 to provide for an optimum length of time in which the gases are contained within the combustor tube 62.

By using the dampers 54 and '55 in laterally spaced independently controlled pairs, I have found it possible to adequately cure the coating on wires of different diameters simultaneously with wires of one diameter being disposed toward one of the side walls 4 and 5, the wires of another diameter being disposed toward the opposite one of the side walls 4 and 5. Further, by providing an oven of the type above-described using a work chamber of a different size and shape than that of the work chamber 30, other objects of various shapes and sizes may be moved through the work chamber for curing of the enamel or other coatings thereon.

While I have shown and described a commercial embodiment of my curing oven, it will be understood that the same is capable of modification, and that modification may be made without departure from the spirit and scope of the invention, as defined in the claims.

What is claimed is: v

1. ln a curing oven for enameled wire:

a. casing means having partition means dividing the interior of the casing means into an elongated work chamber having opposite open inlet and outlet ends for passage of enameled wire through the work chamber, combustor chamber means, and air passage means;

b. an elongated combustor tube disposed in said combustor chamber means and having air inlet openings at one end and opposite open outlet end;

c. said partition means including a wall element separating the combustion chamber outwardly of the combustor tube into an inlet chamber to said inlet openings and outlet chamber containing said open outlet end of the combustor tube;

(1. a burner disposed within the tube adjacent said inlet openings;

e.' said passage means including:

1. an inlet passageway extending from said work chamber intermediate with the inlet and outlet ends thereof to said combustor inlet chamber;

2. and outlet passageways leading from said combustion outlet chamber to said inlet and outlet ends of the work chamber and disposed to direct air in said work chamber to said inlet passagef. a blower for imparting movement of air from said combustor outlet chamber through said passageways, work chamber and combustor tube;

g. and means for admitting air from the exterior of said casing means into said combustor outlet chamber, said passage means including a discharge outlet opening from one of said outlet passages to the exterior of the'casing means.

2. The curing oven defined in claim 1 in which said casing and partition means include portions cooperating to provide a transversely reduced area in said work chamber'and dividing said work chamber into an evaporating zone between the inlet end and said reduced area, and a curing zone between said outlet end and said reduced area.

3. The curing over defined in claim 2 in which said inlet passageway is disposed to communicate with said work chamber adjacent said transversely reduced area, whereby to receive all of the vapor laden air from both of said zones and deliver the same to said combustor inlet chamber.

4. The curing oven defined in claim 2 in which said casing means includes front and rear walls and laterally spaced side walls cooperating with said partition means to define closely spaced front and rear-work chamber walls and widely spaced apart side chamber walls for passage of a plurality of coated wires in spaced apart parallelrelationship through said work chamber, in

further combination with a pair of valve elements disposed in side-by-side relationship in said passage meansand independently operable to control admission of air to said work chamber evaporating zone adjacent a respective one of said widely spaced side chamber walls.

' SI The curing oveh defined i'rreraila'zrfaaamsifiaroh with valve means in said outlet passageway to the outlet end of said work chamber for controlling the flow of .gas from said combustor outlet chamber to the outlet end of said work chamber.

6. The curing oven defined in claim 1 in which said blower defines an inlet opening in communication with said combustor outlet chamber and an outlet opening into said outlet passageway, whereby said blower defines a portion of said outlet passageway. 7. The curing oven defined in claim 6 inwhich said casing means includes a pair of laterally spaced side walls and front and rear walls, said combustor tube and I blower each being disposed relatively close'to a different one of said side walls in relatively widely spaced apart relationship to each other, saidmeans for admit-.

ting air to said combustor outlet chamber comprising a pair of inlet conduits each adjacent a different one-of said combustor tube and blower. g I 7 8, The curing oven defined in claim 7 in further combination with means for controlling passage of air 35 end of said header longitudinally of the skirt in circumthrough each of said inlet conduits to said combustor outlet chamber.

9. The curing oven defined in claim 1 in which said burner comprises a header, a cylindrical skirt at one ferentiallyspaced relationshipto receive fuel from the header, said skirt having a plurality of openings for reception of vapor laden air to the interior thereof from said inlet chamber, and means mounting said burner in 10 the inlet end of said combustor tube, said combustor passageway for flow of vapor'laden air to said burner,

and guide vanes in said annular passageway for directing flow of said air to said burner in a generally spiral direction.

the ends of said combustor tube, said inlet passageway opening into said combustor inlet chamber adjacent said wall element, whereby air entering said combustor inlet chamber travels generally longitudinally of the combustor tube to the inlet openings thereof.

l l, The curing oven defined in claiin l iii Which said wall element is disposed generally centrally between 

1. In a curing oven for enameled wire: a. casing means having partition means dividing the interior of the casing means into an elongated work chamber having opposite open inlet and outlet ends for passage of enameled wire through the work chamber, combustor chamber means, and air passage means; b. an elongated combustor tube disposed in said combustor chamber means and having air inlet openings at one end and opposite open outlet end; c. said partition means including a wall element separating the combustion chamber outwardly of the combustor tube into an inlet chamber to said inlet openings and outlet chamber containing said open outlet end of the combustor tube; d. a burner disposed within the tube adjacent said inlet openings; e. said passage means including:
 1. an inlet passageway extending from said work chamber intermediate with the inlet and outlet ends thereof to said combustor inlet chamber;
 2. and outlet passageways leading from said combustion outlet chamber to said inlet and outlet ends of the work chamber and disposed to direct air in said work chamber to said inlet passageway; f. a blower for imparting movement of air from said combustor outlet chamber through said passageways, work chamber and combusTor tube; g. and means for admitting air from the exterior of said casing means into said combustor outlet chamber, said passage means including a discharge outlet opening from one of said outlet passages to the exterior of the casing means.
 2. The curing oven defined in claim 1 in which said casing and partition means include portions cooperating to provide a transversely reduced area in said work chamber and dividing said work chamber into an evaporating zone between the inlet end and said reduced area, and a curing zone between said outlet end and said reduced area.
 2. and outlet passageways leading from said combustion outlet chamber to said inlet and outlet ends of the work chamber and disposed to direct air in said work chamber to said inlet passageway; f. a blower for imparting movement of air from said combustor outlet chamber through said passageways, work chamber and combusTor tube; g. and means for admitting air from the exterior of said casing means into said combustor outlet chamber, said passage means including a discharge outlet opening from one of said outlet passages to the exterior of the casing means.
 3. The curing over defined in claim 2 in which said inlet passageway is disposed to communicate with said work chamber adjacent said transversely reduced area, whereby to receive all of the vapor laden air from both of said zones and deliver the same to said combustor inlet chamber.
 4. The curing oven defined in claim 2 in which said casing means includes front and rear walls and laterally spaced side walls cooperating with said partition means to define closely spaced front and rear work chamber walls and widely spaced apart chamber walls for passage of a plurality of coated wires in spaced apart parallel relationship through said work chamber, in further combination with a pair of valve elements disposed in side-by-side relationship in said passage means and independently operable to control admission of air to said work chamber evaporating zone adjacent a respective one of said widely spaced side chamber walls.
 5. The curing oven defined in claim 4 in combination with valve means in said outlet passageway to the outlet end of said work chamber for controlling the flow of gas from said combustor outlet chamber to the outlet end of said work chamber.
 6. The curing oven defined in claim 1 in which said blower defines an inlet opening in communication with said combustor outlet chamber and an outlet opening into said outlet passageway, whereby said blower defines a portion of said outlet passageway.
 7. The curing oven defined in claim 6 in which said casing means includes a pair of laterally spaced side walls and front and rear walls, said combustor tube and blower each being disposed relatively close to a different one of said side walls in relatively widely spaced apart relationship to each other, said means for admitting air to said combustor outlet chamber comprising a pair of inlet conduits each adjacent a different one of said combustor tube and blower.
 8. A curing oven defined in claim 7 in further combination with means for controlling passage of air through each of said inlet conduits to said combustor outlet chamber.
 9. The curing oven defined in claim 1 in which said burner comprises a header, a cylindrical skirt at one end of said header longitudinally of the skirt in circumferentially spaced relationship to receive fuel from the header, said skirt having a plurality of openings for reception of vapor laden air to the interior thereof from said inlet chamber, and means mounting said burner in the inlet end of said combustor tube, said combustor tube having openings in its inlet end for passage of said air therethrough from the inlet chamber to said burner.
 10. The curing oven defined in claim 9 in which said means mounting the burner in said combustor tube comprises a generally cylindrical burner mounting conduit in the inlet end of said combustor tube, said conduit having an axial burner receiving opening at one end and an axial discharge opening at its opposite end, said conduit having a perforate cylindrical wall portion cooperating with said burner skirt to define an annular passageway for flow of vapor laden air to said burner, and guide vanes in said annular passageway for directing flow of said air to said burner in a generally spiral direction.
 11. The curing oven defined in claim 1 in which said wall element is disposed generally centrally between the ends of said combustor tube, said inlet passageway opening into said combustor inlet chamber adjacent said wall eLement, whereby air entering said combustor inlet chamber travels generally longitudinally of the combustor tube to the inlet openings thereof. 